1. Field of the Invention
This invention relates to computer systems and, more particularly, to backup and restoration of data within computer systems.
2. Description of the Related Art
There is an increasing need for organizations to protect data that resides on a variety of client devices via some type of backup mechanism. For example, numerous client devices may be coupled to a network to which one or more media servers are also coupled. The media servers may include or be further coupled to a storage unit consisting of one or more disk storage devices, tape drives, or other backup media. Media servers and backup media may provide low-cost, long-term archival storage of data. A backup agent on each client device may convey data files to the media server for storage according to a variety of schedules, policies, etc. Large backup datasets may be moved from a client device to a media server configured to store data for later retrieval, thereby protecting data from loss due to user error, system failure, outages, and disasters, etc. as well as archiving information for regulatory compliance, workflow tracking, etc.
Different backup approaches may be used in different circumstances. For example, if a user desires to protect a complete volume, a volume backup may be performed in which the entire contents of a particular disk drive are stored as a monolithic backup dataset. Volume backups may provide the advantage of rapid restoration. However, volume backups consume storage resources for data that may not need to be protected. For example, there may be times when protection may be desired for data related to one or more applications only.
An alternative approach to data protection is file-by-file backup. In file-by-file backup, a backup agent may identify a particular application to be protected and convey a copy of only those files that are related to the identified application to a backup medium including any metadata that may be required to restore the application-related files into the context of the application. File-by-file backups may therefore consume less storage space than volume backups. However, restoration from a file-by-file backup may be slower than restoration from a volume backup. Typically, to restore files to an application, the backup files may be copied to a temporary location from which a user may browse, search or otherwise select files to be restored. While this approach allows for granular recovery of data files, it may be unnecessarily time-consuming.
File-by-file backups and volume-level backups each have their advantages. However, issues may arise when a user wants the advantages of volume-level backups for some drives, but not for others. For example, if a user wants to protect data for an application that spans multiple volumes and at the same time wants volume-level protection for at least one of the drives, it is difficult for a backup system to satisfy all of the user's needs. If all for the volumes are protected via volume-level backups, storage space may be wasted backing up much more data than is needed. Alternatively, if all of the application's data is backed up using file-by-file techniques in addition to backing up selected volumes using volume-level backup, storage may be wasted storing duplicate data and/or data that the user did not want to be backed up.
In view of the above, an effective system and method for allowing a backup application to efficiently protect data for applications using a variety of storage configurations that accounts for these issues is desired.